1. Field of the Invention
The invention relates to a piston-cylinder assembly, in which a working piston is attached to a piston rod and divides a working cylinder into two working spaces. An external reservoir partially filled with damping medium is provided outside the piston-cylinder assembly and is connected to one of the working spaces by a connecting pipe.
2. Description of the Related Art
Piston-cylinder assemblies, in which the vibration damper comprises a container with an external expansion space connected to the container by a connecting pipe, are known (e.g., DE 102 02 350 C1). The connecting pipe is connected permanently and in a leak-tight manner both to the external reservoir and to the container itself by threaded pipe fittings.
Piston-cylinder assemblies, in which a reservoir partially filled with oil is located externally for space reasons, are also known (e.g., AT 35 445 B). This external reservoir can be attached directly to the piston-cylinder assembly, but it can also be located somewhere else and connected to the piston-cylinder assembly by a flow connection. What is involved here is a gas pressure damper for motorcycles, in which the external reservoir is designed as a gas pressure accumulator, which compensates for the volume of the piston rod. The units are connected to each other by a high-pressure hose with ring-type nipple connections known in the industry, through each of which a banjo bolt passes. This type of connection is bulky and uneconomical and can be disassembled by unauthorized persons. Disassembly at this point makes a piston-cylinder assembly unusable, because the pressurized damping medium escapes.
Additional piston-cylinder assemblies, in which a level-controlled MacPherson strut unit is provided with an external reservoir located outside the MacPherson strut unit, are also known (U.S. Pat. No. 5,797,594). The external reservoir in this exemplary embodiment is used as a low-pressure reservoir, but it is possible to tamper with the pressurized unit. Another source of difficulty is the brazed or welded joint on the assembly side. Pipe connections made by brazing or welding must be inspected for leaks before installation in the vehicle, which increases costs. The cycle times of the assembly process must also be longer, which makes this method of attaching external reservoirs unsuitable for mass production.